This invention relates to an apparatus and method for treating water with ozone, particularly for drinking water and ice making.
It has been well known for many years that water can be purified of harmful organisms by treating it with ozone. However, there is a problem in trying to dissolve ozone in the water to purify it and yet not discharge a significant portion of unreacted ozone from the water, thus wasting it and potentially creating a health hazard.
Four types of gas-liquid contactors have been used for this purpose including spray towers, where liquid is dispersed in a gas, packed beds, bubble plates or sieve towers, and finally units for dispersing gas bubbles in a liquid.
Many of the apparatuses have been designed for industrial purposes, but are not well adapted for use where a relatively compact unit is required for the continuous production of purified water, such as in association with an in-store ice maker or an in-home water purifier.
The use of loop reactors for processes involving liquids and gases has been suggested in such earlier references as U.S. Pat. No. 3,562,349 to Pawloski. In this reference, a pump circulates liquid about a closed loop with inlets and outlets including a gas outlet at the top of the unit.
U.S. Pat. No. 4,252,654 to Leitzke relates specifically to treating water with ozone. Here the water circulated about the loop is split into separate paths for treatment. Only a portion of the total flow of water is treated with ozone by one pass only about the loop. A packed column is employed with a portion of the water sprayed from the top.
Another apparatus for treating water with ozone by circulating it about a loop is shown in U.S. Pat. No. 3,945,918 to Kirk. There is a turbulent zone for mixing the water with ozone as well the setting up of a counterflow of ozone through the water.
My earlier U.S. Pat. No. 5,174,905 discloses a significantly improved ozonator compared with the prior art. However, the efficiency of this ozonator is limited by the maximum flow of water therethrough. It has been found that the flow restriction is due to a number of factors. One of these is the configuration of the restrictor employed for diverting water from the first conduit to the second conduit. Another factor is that if flow was increased too much, the water discharged from the second conduit was expelled from the apparatus along with any excess ozone contained therein.
Accordingly, it is an object of the invention to provide an improved ozonating apparatus which can handle a significantly larger volume flow of water through the ozonator compared with prior art devices of a similar size.
It is also an object of the invention to provide an improved ozonating apparatus which better controls release of excess ozone therefrom.
It is also an object of the invention to provide an improved ozonating apparatus which achieves a more laminar flow of water compared with prior art devices.
In accordance with these objects, there is provided according to one aspect of the invention, an apparatus for treating water with ozone which includes a first conduit and a passageway for admitting ozone into the first conduit. There is a second conduit having a top, an inlet connected to the first conduit and an outlet. There is a third conduit having a top and a vertical portion extending downwardly adjacent to the outlet of the second conduit. The third conduit has a bottom with an outlet below the outlet of the second conduit. There is a passageway connecting the third conduit to the first conduit above the outlet of the second conduit. The passageway is sized to permit a reduced flow of water through the third conduit compared to the flow through the second conduit and provides means for ozone discharged from the outlet of the second conduit to rise through the vertical portion of the third conduit to increase dissolving of the ozone in the water. There is a pump with sufficient capacity to force a stream of water and undissolved ozone from the outlet of the second conduit so said stream reaches a point at least one-half the distance from the outlet of the second conduit to the outlet of the third conduit, but less than the distance from the outlet of the second conduit to the outlet of the third conduit, before the undissolved ozone circulates upwardly.
The apparatus may include a restrictor for diverting water from the first conduit into the second conduit, the first conduit including an elbow connected to to the second conduit, the elbow of the first conduit having a curved interior with an inside radius, the restrictor having a curved interior which is aligned with the interior of the elbow of the first conduit and forms a smooth curve with the inside of the elbow of the first conduit adjacent to the inside radius.
Preferably the apparatus forms a loop with a conduit extending from near the outlet of the second conduit to the pump.
There may be an outlet for gas near the top of the loop.
In a preferred form of the invention, the second conduit is inside the third conduit.
According to another aspect of the invention an apparatus for treating water with ozone includes a first conduit with a passageway for admitting ozone into the first conduit.
There is a second conduit having an inlet connected to the first conduit and an outlet. There is a third conduit having a top which is above the first and second conduits. The third conduit has a horizontal portion adjacent to the top and a vertical portion extending downwardly from the top.
There is a passageway connecting the third conduit to the first conduit. The passageway is sized to permit a reduced flow of water through the third conduit compared to the flow through the second conduit and provides means for ozone discharged from the outlet of the second conduit to rise through the vertical portion of the third conduit to increase dissolving of the ozone in the water. There is means for pumping water through the conduits. An ozone relief valve at the top of the third conduit is opened by an accumulation of ozone adjacent thereto.
For example, the ozone relief valve may include a float mechanism having a float, the ozone relief valve being opened when the float drops.
The invention offers significant advantages compared to the prior art. By positioning the outlet of the second conduit well above the outlet of the third conduit, the rate of pumping can be significantly increased. This leads to significantly increased ozonating capacity compared to the prior art. If the pumping rate had been increased in earlier apparatuses of the general type, this would have resulted in the undissolved ozone being directed through the outlet of the third conduit and back to the pump, causing cavitation and therefore pump dysfunction. Moving the outlet of the second conduit upwardly, compared to the prior art, allows a stream of water and undissolved ozone sufficient room to move downwardly so that the ozone can begin to bubble upwardly before reaching the outlet of the third conduit.
Employing an ozone release valve actuated by afloat prevents an undesirable accumulation of undissolved ozone at the top of the apparatus which may occur with some prior art devices. Excess ozone is automatically bled off where it can be destroyed by activated carbon or similar utility substances.
The stated above, preferably the restrictor has a curved interior which is aligned with the interior of the elbow of the first conduit and which forms a smooth curve with the inside of the elbow of the first conduit adjacent to the inside radius. This construction provides a much more laminar flow through the restrictor and accordingly allows a substantially increased pumping capacity. The increased pumping capacity leads to substantially increased ozonating capacity.